Jeremy Maclin figured to be one of the focal points in Chip Kelly's new up-tempo offense. (Damian Strohmeyer/SI)

Jeremy Maclin tore the ACL in his right knee during the Philadelphia Eagles' Saturday practice, a development that could deliver a major blow both to the Philadelphia Eagles' offense and to Maclin's quest for a new contract. The team confirmed Maclin's injury on Twitter, mere hours after Maclin had to be carted from the practice field at training camp.

Maclin's five-year, rookie deal with the Eagles expires after this season. The two sides made no real progress this offseason on extending Maclin beyond 2013 -- and, to his credit, Maclin has refused to turn that uncertainty into a black cloud, instead stating repeatedly that he planned to prove his worth before possibly hitting free agency.

The situation obviously has changed now, with Maclin's future even more up in the air than before.

Exactly where the Eagles' offense goes from here is a bit of a mystery, too. Maclin again was set to pair with DeSean Jackson to give the Eagles a dynamic 1-2 punch at receiver. And with new coach Chip Kelly's arrival bringing the promise of a more creative offense, Maclin was in line for a substantial role.

However, the possible replacements for Jackson are a bit of a rag-tag group. Steady veteran Jason Avant ought to stay in the rotation, with Jackson; beyond that, Philadelphia will turn to some combination of Riley Cooper, Arrelious Benn (who hyperextended his knee Friday), Damaris Johnson, Greg Salas and others to fill the void in the immediate future. The free-agent market has been piked mostly bare at receiver, with Brandon Lloyd, Laurent Robinson and Donald Jones among the uninspiring choices.

Philadelphia does have an intriguing group of tight ends in Brent Celek, Zach Ertz and Clay Harbor, plus the versatile James Casey. Kelly already had hinted at the possibility of more two- and three-tight end sets, and he may head full bore in that direction with Maclin's fate for 2013 sealed.

Ironically, Maclin's injury history may be part of why the Eagles have shied away from offering him a contract extension thus far. Though Maclin has averaged 64.5 catches and 863 yards receiving in his four seasons with Philadelphia, he's also missed five games and landed on the injury report constantly last season with multiple ailments (back, groin and hip, to name a few).

All those dings were minor compared to his newest injury.

"Appreciate all the love and support twitter fam," Maclin tweeted late Saturday afternoon. "sad day but I have setbacks my entire life. Minor setback for a MAJOR comeback! #birdgang"

The questions for Maclin are when that comeback will occur and which team he'll be playing for when it does. Even if Maclin is ready in time for the 2014 season, he may have to convince a team to give him a shot. The Eagles could put a one-year deal on the table, in time, giving Jackson a do-over on his prove-your-worth season.

For now, though, Maclin is facing several months of rehab, while the Eagles must find some way to fill his spot on the field.